To reduce engine fuel consumption and emissions, vehicles are continually being adapted to operate more efficiently. One mechanism to improve vehicle efficiency includes operating certain accessory components of the vehicle, such as air conditioning compressors, electrically instead of mechanically via the engine of the vehicle. However, the additional electrical load on the vehicle frequently necessitates electricity generation via the vehicle alternator, which may degrade fuel consumption and emissions.
Various approaches to generating electricity onboard a vehicle have been proposed. In one example shown by Mitkari et al. in U.S. Patent Application Publication No. 2017/0074157, thermoelectric generators are coupled to a wastegate enclosure of a turbocharger turbine. The thermoelectric generators generate electricity via heat flux from a high temperature region (the wastegate enclosure) to a low temperature region (a coolant supply), and the electricity may be used by accessory components or stored in a battery.
However, the inventors herein have recognized some issues with the above approach. Due to the positioning of the wastegate enclosure, the additional coolant supply is required to generate a sufficient temperature differential across the thermoelectric generators. The provision of the additional coolant supply may increase the cost and complexity of such a system. Further, only a portion of the exhaust gas from the engine may flow through the wastegate, and only at certain operating conditions, such as high load conditions, and thus the system of Mitkari fails to take advantage of other sources of waste heat in the exhaust system. Further still, Mitkari fails to recognize that because the thermoelectric generators generate current in proportion to the temperature differential across the thermoelectric generators, the presence of the thermoelectric generators in certain locations of the vehicle presents an opportunity to utilize the thermoelectric generators as sensors to monitor performance of some vehicle or engine components.
Accordingly, the inventors herein provide an approach to at least partly address the above issues. In one example, a method includes adjusting one or more engine operating parameters based on an amount of current generated from one or more thermoelectric generators coupled to a turbocharger. In this way, the amount of current generated by the one or more thermoelectric generators may be monitored to determine if the temperature differential across the thermoelectric generators corresponds to an expected temperature differential. In one example, because the thermoelectric generators are coupled to a turbocharger, the expected temperature differential may reflect an expected temperature of a turbine of the turbocharger. If the amount of current generated by the one or more thermoelectric generators is greater than expected, a greater than expected temperature differential may be indicated that reflects a high turbine temperature. In response to the high turbine temperature, a wastegate position may be adjusted to direct high temperature exhaust gas away from the turbine and/or engine torque may be limited to reduce exhaust gas mass flow and temperature.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.